Method for processing cellulosic fibre material

ABSTRACT

TEXTILE ARTICLES COMPOSED PARTIALLY OR TOTALLY OF CELLULOSE FIBRES ARE IMPROVED BY (A) SWELLING THE FIBRES BY MEANS OF AN AQUEOUS SOLUTION OF A COMPOUND WHICH INTERRUPTS HYDROGEN BONDING SUCH AS ORGANIC OR INORGANIC BASE THE CONCENTRATION OF SUCH SOLUTION BEING SUCH AS TO LIMIT THE SWELLING TO A DETERMINED LEVEL; (B) REPLACING THE AQUEOUS SWELLING SOLUTION WITHIN THE SWOLLEN FIBRE PROGRESSIVELY BY A SERIES OF LIQUIDS, THE FIRST OF WHICH IS MISCIBLE IN ALL PROPORTIONS WITH WATER SUCH AS AN ALCOHOL, ACETONE, DIOXAN, AND THE LIKE, AND THE LAST OF WHICH IS MISCIBLE IN ALL PROPORTIONS WITH THAT WHICH PRECEDES IT SUCH AS AN AROMATIC HYDROCARBON AND WITHOUT VARIATION OF THE INITIAL STATE OF SWELLING; (C) INCLUDING INTO THE FIBRE A RELAITIVELY ELASTIC SUBSTANCE WHICH HAS AN INITIAL MODULUS OF ELASTICITY LOWER THAN OF CELLULOSE SUCH AS ISOPRENE, BUTADIENE, AND THE LIKE.

United States Patent 3,674,539 METHOD FOR PROCESSING CELLULOSIC FIBRE MATERIAL Andre Parisot, Saint-Cloud, and Daniel Meimoun, Rueil- Malmaison, France, assignors to Institut Textile de France, Bonlogne-sur-Seine, France No Drawing. Filed Aug. 12, 1969, Ser. No. 849,490 Claims priority, application France, Aug. 14, 1968, 163,110 Int. Cl. B44d 1/092 US. Cl. 117-56 16 Claims ABSTRACT OF THE DISCLOSURE Textile articles composed partially or totally of cellulose fibres are improved by (a) swelling the fibres by means of an aqueous solution of a compound which interrupts hydrogen bonding such as an organic or inorganic base the concentration of such solution being such as to limit the swelling to a determined level;

(b) replacing the aqueous swelling solution within the swollen fibre progressively by a series of liquids, the first of which is miscible in all proportions with water such as an alcohol, acetone, dioxan, and the like, and the last of which is miscible in all proportions with that which precedes it such as an aromatic hydrocarbon, and without variation of the initial state of swelling;

(0) including into the fibre a relatively elastic substance which has an initial modulus of elasticity lower than of cellulose such as isoprene, butadiene, and the like.

This invention relates to a method for processing cellulosic fibres (as a fibrous mass, thread, fabric or mesh articles comprising partially or totally cellulosic fibres) in order to improving their textile properties, and in particular their crease-resistance properties. By creaseresistance is meant both resistance to the initiation of creasing, and recovery from any creasing which is imparted.

It is well established nowadays that alteration in cellulosic textile fibre structure brings about variations in fibre properties, and consequent modification of the properties of fabrics or textile articles formed of these fibres. Knowledge of the relationship between the fibre structure and textile properties is the basis for designing any process of obtaining a predetermined modification.

Known processing methods, which are particularly valuable for obtaining crease-resistance may be classified into the two general types given below:

(i) The random introduction of an additional substance of high molecular weight into the cellulosic structure to which said substance may subsequently become bound; and,

(2) The direct interconnection of components of the cellulosic structure by means of bi-, trior multifunctional molecules establishing cross-linking.

Experience shows that when the said components of the cellulosic structure are macromolecules of cellulose, the properties and in particular the flexural properties of the fibre become undesirably changed as a result of the transformation of the monodimensional structure of the cellulose molecule into bi-, or tri-dimensional systems with high transverse modulus. Because of this, the practical working life of apparel fabrics is shortened.

The invention concerns in general terms, a method involving the inclusion in cellulosic fibres (cotton, flax, jute, viscose and so on) whether pure or mixed, of a substance with an initial modulus of elasticity which is less "ice limit this swelling by adjusting the concentration of the solution:

(a) either to the level of the inter-fibrillary capillary spaces (b) or to the level of the inter-micellary spaces in the fibrils (c) or to the level of the inter-molecular spaces in the fibrils.

By progressive replacement of the aqueous swelling solution by a series of inclusion liquids, the first liquid of which series is miscible in all proportions with water, and the last liquid of which series is miscible in all proportions with that which precedes it, without variation of the initial state of swelling, it is possible to introduce the inclusion substance into the cellulosic fibres, at the level desired.

The invention more particularly comprises a method by which it is possible to introduce an inclusion substance, having an initial modulus of elasticity less than that of cellulose, specifically into the inter-fibrillary spaces level (a) of the cellulose fibres (cotton, flax, jute, viscose and so on) but to avoid any penetration of the substance to the interior of the fibrils (i.e. into the inter-micellary spaces and into the inter-molecular spaces in the fibrilslevels (b) and (c) defined above) and therefore any structural modification at the molecular level of the cellulose. Moreover, as the included substance has a modulus of elasticity lower than that of the cellulosic fibre, the transverse modulus of the fibre will not be altered, but its recovery from flexural deformation will be improved.

The invention accordingly makes it possible to give fabrics better crease-resistant, including crease-recovery, properties.

The method of the invention consists in that:

(a) The cellulosic fibres are processed by means of an aqueous solution of an inorganic or organic base (or other) interrupter of the hydrogen bonding by controlling the concentration of such solution in such a manner as to limit the swelling to the level of the inter-fibrillary spaces of the fibres without internal swelling of the fibrils.

(b) The aqueous swelling solution is replaced progressively by a series of inclusion liquids, the first liquid of which series is miscible in all proportions with water, and the last liquid of which series is miscible in all proportions with that which precedes it, and without variation of the swelling from the initial swelling state, the last inclusion liquid containing an inclusion substance with initial modulus of elasticity which is less than that of cellulose.

The initial modulus of elasticity is the value of the slope of the straight tangent to the origin of the load/extension curve. For cellulose fibre, the average value of the initial modulus of elasticity is approximately 75,000. Preferred inclusion substances are those where the modulus of elasticity is lower than times, or preferably lower than A times the cellulose value. [Elastomers are to be preferred.

In particular, the last inclusion liquid may comprise a monomeric precursor of an elastomer, together with an be stabilised by suitable washing and/ or extraction treatments.

In accordance with a first variation of the method of the invention, the last inclusion liquid contains an initiator and a catalyst for polymerisation, and after its inclusion has taken place, the cellulosic fibres are exposed to the action of monomer vapour.

A second variation of the method of the invention involves using a pre-polymerisate of the elastomer in the form of an emulsion, then in bringing about in situ the coagulation of the elastomer in one homogeneous phase, the other second, phase of the initial emulsion being eliminated by appropriate Washing or extraction treatments.

A third variation consists in creating at the surface of the walls of the fibrils, before the inclusion of the monomer, initiator and catalyst either active polymerisation sites or regions of unsaturated bonding which are able to participate in the polymerisation process.

A fourth variation consists in including a solution of the first monomer, and then padding-in (foulardage) of a solution of a second monomer different from the first, with subsequent interfacial polycondensation in the spaces to provide a polycondensate elastomer.

The compound which interrupts the hydrogen bonding may be an inorganic base, such as soda, potash, lithium hydroxide, caesium hydroxide, or an organic base, such as a fatty amine, ethanolamine, or morpholine. As the series of inclusion liquids, use may be made of methanol followed by benzene. However, instead of or in series with another alcohol, or organic solvent soluble both in water and in hydrophobic solvents (such as acetone or dioxan) can be used. The benzene may be replaced by another aromatic hydrocarbon (toluene, xylene and so on), or indeed any hydrophobic solvent capable of holding the elastomer or its precursors in solution.

As a monomeric precursor for the elastomer, use may be made of isoprene, butadiene or other conjugated diene, or an isocyanate/diol combination.

As alread mentioned above, the nature of the swelling of the cellulosic fibres depends on the concentration of the aqueous base solution used, and may involve (a) the inter-fibrillar capillary spaces, (b) the inter-micellary spaces in the fibrils or (c) the inter-molecular spaces in the fibrils.

The suitable concentration of swelling agent used in accordance with the invention should be specific for phase a to the exclusion of phases b and c. It depends on the nature of the base used and may readily be determined by previous swelling tests and examination of the swollen test fibres with an electron microscope.

With sodium hydroxide in aqueous solution, the specific concentrations of the phases a, b and c respectively should usually be 4%, 8% and 18% the percentages being by weight. A suitable concentration of the aqueous solution of soda should accordingly be less than 8%, so that there is no penetration of the swelling agent in the inter-micellary spaces and inter-molecular spaces of the fibrils. For potash in aqueous solution, this preferred suitable concentration is less than and for lithium hydroxide, the preferred suitable concentration is less than 6% by weight.

The following examples are given to illustrate the invention but without at all limiting its scope to one that is defined in the appended claims.

4 EXAMPLE 1 l) Swelling of the fibres A cotton fabric carefully boiled by a standard treatment method is processed using an aqueous 5% solution of sodium hydroxide for a period not exceeding 3 hours. The swollen material is rinsed in pure water until a neutral reaction is obtained, and then immersed in a series of baths of anhydrous methyl alcohol until total substitutions of the water contained in the fabric by anhydrous methanol was achieved.

(2) Replacement (3) Polymerisation The process of polymerisation is then started by raising the temperature above the decomposition temperature of the peroxide, which is about C.

(4) Elimination of the excess of reagents After polymerisation, the fabric is washed in benzene to eliminate excess reagents, then treated in an alcoholic solution of B-nap-hthol as anti-oxidising agent for the included polymer.

The fabric, treated in this way shows under mechanical checking improved crease-resistance without notable loss in mechanical resistance.

Treated Control sample sample Remanent angle (warp and weft) degree No'rE.Loss of resistance to cracking, 20%.

EXAMPLE 2 A fabric based on cellulosic fibres and previously having been subjected to various standard pro-treatments is swollen by a cold 3% solution of lithium hydroxide for a period not exceeding 3 hours.

The swollen material is rinsed with water and immersed in a bath of anhydrous methyl alcohol. Every 3 hours, the alcohol is renewed until there is total inclusion of anhydrous methanol in place of water. Thereafter the inclusion of anhydrous benzene, is carried out by the same replacement process. The material with the benzene thus included, is immersed in a 5% benzene solution of maazo-bis-bntyronitrile (1% to 5%) for a period which may bridge 15 hours.

The sample is thereafter stretched on a metallic frame and placed in an atmosphere of butadiene vapour in an autoclave. Polymerisation is started by raising the temperature to 60 C. and the sample is kept at this state for 24 hours.

After polymerisation, the excess of reagents is eliminated as in Example 1. One obtains:

Treated sample Control sample Remanent angle (warp and weft), degree NorE.-Loss of resistance to cracking, 20%.

EXAMPLE 3 Treated sample Control sample Remanent angle (Warp and weft), degree Norm-Loss oi resistance to cracking, 20%.

EXAMPLE 4 A fabric based on cellulosic fibres is swollen by a 10% aqueous solution of potassium hydroxide after having been subjected to standard wax removing and desizing operations.

The material treated in this way is then treated with anhydrous methanol and subsequently with benzene, as described in Example 1 to give benzene inclusions and thereafter treated with a 30% solution (5% to 50% is usable) of a di-isocyanate such as a diisocyanate of the formula O=C=NDN=C=O where in D represents an unsaturated hydrocarbon with 36 carbon atoms (Mills Company 1 410 G) in benzene. It is then padded, at a rate of liquid expressed such as to keep in its structure only an amount of product not exceeding 20% in relation to the weight of cellulosic material to be processed. The material is then immersed in an alcoholic solution of ethylene glycol and padded fiat after up to one hours immersion.

The material is then dried and polymerised, with or without tensioning in a drying stove at a temperature of about 120 C. to 140 C.

After polymerisation, the excess of reagent is eliminated as described in Example 1.

N orE.-Loss of resistance to cracking,

EXAMPLE A cotton fabric, which had been subjected to the various preliminary operations mentioned in Example 1 (swelling, inclusion of methanol and then of benzene) is immersed in a benzene solution of allyl bromide, protected from the light, in an inert atmosphere, for several hours. Allyl cellulose becomes formed at a substitution rate which may vary from 0 to 0.6 (by celluglucane determination). On the material thus obtained, the cycle of operations of stages 2, 3 and 4 described above can be effected.

We claim:

1. A method for processing cellulosic fibre material in order to improve its crease resistance properties, comprismg:

(i) contacting the cellulosic fibre material with an aqueous solution of a compound which disrupts hydrogen bonding in order to swell the fibre by take-up of water, the aqueous solution being of a strength such that swelling is effected in the interfibrillar spaces of the fibre but not within the fibrils,

(ii) replacing the aqueous liquid in the swollen fibre by a series of substantially anhydrous organic inclusion liquids, a first substantially anhydrous organic liquid thereof being miscible in all proportion with Water, the second substantially anhydrous organic liquid thereof being miscible in all proportions with said first liquid, and the last liquid thereof being a substantially anhydrous organic solvent miscible in all proportions with that liquid which precedes it in 6 the series, sad last liquid containing an initiator anda catalyst for subsequent polymerisation reaction,

(iii) incorporating into the interfibrillar spaces containing said last liquid at least one olefinic monomeric precursor of an elastomer which has an initial modulus of elasticity lower than that of cellulose, and

(iv) effecting the polymerisation until said elastomer is formed within the interfibrillar spaces of the cellulosic fibre material.

2. A method as claimed in claim 1, wherein prior to the incorporation of said monomeric precursor, active polymerisation sites are formed on the walls of the interfibrillar spaces.

3. A method as claimed in claim 2, wherein prior to the incorporation of said monomeric precursor, initiator and catalyst, regions of unsaturated bonding are formed on the walls of the interfibrillar spaces.

4. A method as claimed in claim 1, wherein the compound which disrupts the hydrogen bonding is an organic base.

5. A method as claimed in claim 4, wherein the organic base is chosen from fatty amines, ethanolamine and morpholine.

6. A method as claimed in claim 1, wherein the compound which disrupts the hydrogen bonding is an inorganic base.

7. A method as claimed in claim 6, wherein the inorganic base is chosen from sodium, potassium, lithium and caesium hydroxides.

8. A method as claimed in claim 1, wherein the series of inclusion liquids include (a) an organic solvent soluble in water and in hydrophobic solvent and (b) a hydrophobic solvent.

9. A method as claimed in claim 8, wherein the inclusion liquids include: (a) a water-soluble akanol also soluble in hydrocarbon solvents and (b) a hydrocarbon solvent.

10. A method as claimed in claim 8, wherein the inclusion liquids include (a) methanol and (b) benzene.

11. A method as claimed in claim 1, wherein the monomeric elastic precursor is a conjugated diene.

12. A method as claimed in claim 11, wherein the conjugated diene is isoprene or butadiene.

13. A method as claimed in claim 1, wherein the aqueous solution is a sodium hydroxide solution of up to 8% concentration by weight.

14. A method as claimed in claim 1, wherein the aqueous solution is a potassium hydroxide solution of up to 15% concentration by weight.

15. A method as claimed in claim 1, wherein the aqueous solution is a lithium hydroxide solution of up to 6% concentration by weight.

16. A method for processing cellulosic fibre material morder to improve its crease resistant properties, comprising:

(i) contacting the cellulosic fibre material with an aqueous solution of a compound which disrupts hydrogen bondmg in order to swell the fibre by take-up of water, the aqueous solution being of a strength such that swelling is effected in the interfibrillar spaces of the fibre but not within the fibrils,

(ii) replacing the aqueous liquid in the swollen fibre by a series of substantially anhydrous organic inclusion liquids, a first substantially anhydrous organic liquid thereof being miscible in all proportions with water, the second substantially anhydrous organic liquid thereof being miscible in all proportions with said first liquid, and the last liquid thereof being a substantially anhydrous organic solvent miscible in all proportions with that liquid which precedes it in the series, said last liquid containing an initiator and a catalyst for a subsequent polymerisation reaction,

(iii) incorporating into the interfibrillar spaces containing said last liquid at least one olefinic monomeric precursor of an elastomer which has an initial modulus of elasticity lower than that of cellulose and a diisocyanate of the formula References Cited UNITED STATES PATENTS Taylor et a1. 117-56 Gensel et a1. 117-56 X Hagge et a1 117-56 X Buchanan et a1. 117-56 X Gensel et a1 117-161 X Bridgeford 117-62.2 X Thoma et a1 117-161 X FOREIGN PATENTS 4/ 1934 Great Britain 117-56 6/1938 Great Britain 117-56 6/ 1940 Great Britain 117-56 4/ 1941 Australia 117-56 OTHER REFERENCES Fourt, Lyman et aL: The Improvement of Luster of Cotton, pp. 11-19, January 1955.

WILLIAM D. MARTIN, Primary Examiner M. R. LUSIGNAN, Assistant Examiner US. Cl. X.R.

8-1156, 116.2, 120, 125, 130.1, DIG. 11, 18; 117-60, 62.1, 143 A, 161 KP 

